Field of the Invention
The present invention relates to a system for spot welding performed by a robot.
Related Art
Conventionally, robot systems for performing spot welding are operated at various places, for example, a vehicle body assembly process at an automotive factory. In such a robot system, when a robot reaches a welding position, a pressure command is issued to a welding gun, and when a pressure force feedback reaches a preset pressure force, a welding command is issued to a welding machine. The welding machine starts to perform welding upon reception of the welding command, and terminates the welding and notifies the robot of the completion of the welding after a welding time set as a welding condition elapses. The robot maintains a pressure force during the welding, and releases the welding gun and moves to the next welding position upon reception of notification of the completion of the welding. The series of such operation includes a required pressuring time from when pressuring is commanded to when the pressuring is completed, as an example, and the time corresponds to a standby time of the welding machine, which affects a cycle time of welding. To deal with this, for example, a method of controlling the timing of the pressure command in consideration of the required pressuring time taken the welding gun (for example, refer to Patent Document 1 and Patent Document 2) is proposed.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H06-023561
Patent Document 2: Japanese Unexamined Patent Application, Publication No. H11-320116